Generally, an image forming apparatus such as a laser printer which employs a belt for feeding sheets or performing an intermediate transfer has been well known. The aforementioned image forming apparatus is generally provided with a belt cleaning unit equipped with a roller and a brush to remove foreign matters adhered onto the belt, for example, toner or paper dust. Preferably, such a cleaning unit is configured to be easily replaceable in consideration for maintenance or product life.
In the case where the replaceable cleaning unit is employed, the image forming process may be performed while the cleaning unit is left uninstalled. When the image forming is performed by the image forming apparatus without the cleaning unit installed, it may have the trouble with the resultant print because neither the residual toner nor the paper dust can be removed by the cleaning unit. The sensor for detecting the uninstall state of the cleaning unit may solve the aforementioned problem. Such a sensor, for exclusive use of the cleaning part, may increase the number of parts to be added, resulting in the cost increase.
Thus, there is a need in the art for a structure in which the cleaning unit is replaceable for improving the maintenance performance, and which allows for easy detection of the uninstall state of the cleaning unit and is cost effective.